Constraints on the global structure of magnetic clouds: Transverse size and curvature

By Ying Liu, John D. Richardson, John Winston Belcher, Chin-Liang Wang, Qiang Hu, J. Kasper. 2006

139 citations recorded by the source corpus.

We present direct evidence that magnetic clouds (MCs) have highly flattened and curved cross section resulting from their interaction with the ambient solar wind. Lower limits on the transverse size are obtained for three MCs observed by ACE and Ulysses from the latitudinal separation between the two spacecraft, ranging from 40 degrees to 70 degrees. The cross-section aspect ratio of the MCs is estimated to be no smaller than 6:1. We offer a simple model to extract the radius of curvature of the cross section, based on the elevation angle of the MC normal distributed over latitude. Application of the model to Wind observations from 1995 to 1997 (close to solar minimum) shows that the cross section is bent concavely outward by a structured solar wind with a radius of curvature of similar to 0.3 AU. Near solar maximum, MCs tend to be convex outward in the solar wind with a uniform speed; the radius of curvature is proportional to the heliographic distance of MCs, as demonstrated by Ulysses observations between 1999 and 2003. These results improve our knowledge of the global morphology of MCs in the pre-Stereo era, which is crucial for space weather prediction and heliosphere studies.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/99a6be71d04c896b465c5592824716256f22d39a

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In Astronomy and Astrophysics

1. N. Lugaz
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4. J. Davies
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8. Jan Luhmann

Citations in the corpus

• RECONSTRUCTING CORONAL MASS EJECTIONS WITH COORDINATED IMAGING AND IN SITU OBSERVATIONS: GLOBAL STRUCTURE, KINEMATICS, AND IMPLICATIONS FOR SPACE WEATHER FORECASTING (2010, background): “CMEs can be significantly distorted by ambient coronal and solar wind structures (Liu et al. 2006a, 2008a, 2009b); even a uniform solar wind can easily flatten the cross section with its radial flow (Riley & Crooker 2004; Liu et al. 2006a).”
• The Physical Processes of CME/ICME Evolution (2017, background): “Departures from force-free equilibrium are common in ICMEs, providing an overpressure that can drive expansion (Liu et al. 2006a).”
• Origins of the Ambient Solar Wind: Implications for Space Weather (2017, background): “As these processes are identified and characterized, we also expect improvements in models of CMEs, which have proposed heating mechanisms (see, e.g., Liu et al. 2006; Murphy et al. 2011) very similar to those discussed in Sect.”
• GEOMETRIC TRIANGULATION OF IMAGING OBSERVATIONS TO TRACK CORONAL MASS EJECTIONS CONTINUOUSLY OUT TO 1 AU (2010, methodology): “The MC radial width (average speed times the duration) is about 0.1 AU, relatively small compared with the average level 0.2 - 0.3 AU at 1 AU (e.g., Liu et al. 2005, 2006b).”